1. Field of the Invention
The present invention relates generally to electrical circuits and, more specifically, the present invention relates to electrical circuit trimming.
2. Background Information
In electrical circuit manufacture, it is often desirable to trim the circuit operation after the circuit is assembled in order to compensate for manufacturing tolerances. Known techniques to achieve trimming of electrical parameters at final assembly include the use of trimming potentiometers which add circuitry, are prone to instability (under mechanical/thermal stress) and also require human interaction to provide the adjustment. Other techniques include the use of wire links bumpers) or resistors assembled onto the printed circuit board and subsequently disconnected (or clipped) to trim circuit parameters. These techniques add cost and complexity since they often require human interaction to provide the trim and add components to the electrical circuit.
Known power supplies employ sensing of the output voltage and or current of the power supply to provide a feedback signal. The feedback signal is then used by a switching regulator to accurately control the output characteristic. Typically, such power supplies employ direct output voltage and current sensing. Other configurations employ an indirect sensing of the output, often using the windings of the transformer to derive information about the output. The indirect sensing techniques are sometimes attractive as they eliminate some circuitry. However, indirect sensing techniques typically suffer from poorer voltage and current regulation accuracy since the feedback information is influenced by other factors such as transformer manufacturing tolerances, which are difficult and expensive to improve.
Electrical circuit trimming methods are disclosed. In one aspect of the invention, a trimming method includes assembling one or more components of an electrical circuit onto a printed circuit board having one or more electrical connections coupled to the said one or more components. An electrical parameter of the electrical circuit is then trimmed. The trimming of the electrical parameter of the electrical circuit includes removing a portion of the printed circuit board to break the electrical connection on the printed circuit board. Additional features and benefits of the present invention will become apparent from the detailed description, figures and claims set forth below.